This invention relates to methods of making a python, that is to say a bundle of tubes encased in a foam sheath such as is used for the conveyance of beverages from cellar or cool store to a dispensing point such as a bar or soft drinks counter.
Such bundles of tubes are required to be of surprisingly substantial length, and are used normally in lengths up to and exceeding 100 meters. The tube bundles are sheathed in a foam insulating material so as to maintain their low temperature up to the dispensing point, where they may need "flash" cooling or maybe heating immediately prior to dispensing in order to be served at the correct temperature.
The tube bundles, of "food grade" plastics material for the conveyance of beverages and such additional "service", e.g. coolant tubes such as may be required, are assembled into a bundle and wrapped, usually in a cling-film material. The bundles are assembled to particular requirements, some at least being standard or substantially so by virtue of their being widely specified by brewery chains or like enterprises.
As described in GB 2 166 833A, great difficulties are experienced in fitting the foam sheath onto the bundle of tubes. The practice of lubrication using talc is said there to be undesirable, but another problem is said to be that only short lengths of sheath can be pulled over the tube bundle, each length requiring to be accurately butted to its neighbor. The use of such short lengths is dictated clearly by the difficulty of using long lengths, and not, as suggested in GB 2 166 833A, because only short lengths, of a few meters, were available.
In any event, the problem is solved, according to GB 2 166 833A, by first slitting the foam sheath along its length and introducing the bundle via the slit, which is then adhesively repaired. This solution has in fact been widely adopted.
Difficulties occasionally arise in practice with this method, when the repaired slit constitutes a continuous line of impaired thermal resistance along which condensate can form in considerable quantity. The condensate then drips from the outer wrapping of the python and has obvious deletrious effects on the structure through which the python passes.